Don't ever buy a watch with 21mm lug spacing unless you at the same time buy a lifetime supply of straps for it.
Spring is almost here so at any time there may be a rideable moment. I'm following the Iditarod Sled Dog Race, so out on my bike I wanted a watch with dual time so I could tune in for the finish. I have at least five such watches because dual time or world time is a common complication on pilot's and businessmen's watches. But three are Citizen Eco-Drives which spent 30 years on the window-sill being charged and were then put away when I stopped flying. Result: Flat batteries and rotted leather straps. That leaves two mechanical dual time watches, one of which is so heavy despite being carved out of alloy that it just isn't bike wear. That leaves one, with 21mm lugs, from which I earlier cannibalized the strap to another Citizen Eco-Drive watch, a minute repeater, with predictable results. A 21mm strap is not something for which you pop down to the local jeweler in a small town; the accepted strap width standard is even numbers. So the two straps you see in the biccie are 22mm, which I make fit by bending them a bit in the middle at the lug end to get them in, and use a proper 21mm spring pin. Unfortunately, both straps had served windowsill time on Eco-Driver Citizens, and as a consequence deconstructed themselves.
Brooks Proofide to the Rescue! I glued the straps together again, let them dry, found them pretty ugly, not up to the standard expected for an accessory to my bike, and wondered about neatsfoot oil. But I'd recently had a lecture from my dermatologist about not exposing my skin to UV and other dangers, and who knows what is in neatsfoot oil. On the other hand, I sit on Proofide and I've never heard anything bad about it, so I gave the straps a thin layer of Proofide on top, and just a light wipe with the same cloth on the underside, let it sink in overnight, and then today buffed up the straps.
They came up rather well: